Terminal arrangement for integrated circuit device

ABSTRACT

An integrated circuit includes electrically conductive terminals arranged to be connected to external leads for communication between the leads and the circuitry of the integrated circuit device. The terminals of the circuit device are disposed at a surface away from the perimeter of the integrated circuit device so that the terminals are arranged in a specified area that is small compared to the overall area of the integrated circuit device, preferably in the center of a surface of the integrated circuit device.

This application is a division of application Ser. No. 07/117,541, filed11-6-87, now U.S. pat. No. 4897,534.

The present invention relates to a data carrier having at least one ICmodule for processing electrical signals, the IC module being disposedon a substrate which is small compared to the area of the data carrier,communicating via leads with contact elements also provided on thesubstrate which allow for communication of the IC module withcorresponding machines and being disposed in a recess in a central cardlayer.

A data carrier of the above-mentioned kind is disclosed, for example, inGerman "offenlegungsschrift" no. 33 38 597.

In the known data carrier the substrate bearing the IC module, the leadsand the contact surfaces is laminated into a multilayer identificationcard using heat and pressure in such a way that the IC module is locatedin the interior of the card while the contact surfaces are flush withthe surface of the card.

The structural shape used for the integrated circuit in German"offenlegungsschrift" no. 33 38 597 is a so-called micropack. Thesubstrate is generally made of a meterial (e.g. polyimide) which doesnot combine with conventional card materials. A melt adhesive or a meltadhesive film is therefore used to interconnect the various syntheticmaterials using heat and pressure.

Although the melt adhesive film mentioned in German"offenlegungsschrift" no. 33 38 597, being a resilient soft layer in theform of a buffer zone, does tend to protect the circuit, it has turnedout in practice that this protective effect does not meet the desiredrequirements especially in the case of integrated circuits with largerdimensions which, due to their dimensions, are exposed to strongerbending forces during use of the card. One reason for this is that themelt adhesive film must be relatively thin, which necessarily restrictsthe protective effect as a buffer zone. If the film is thicker, meltadhesive material is inevitably squeezed out at the edge areas of thesubstrate when the card layers are being pressed together, reaches thesurface of the card and impairs the appearance of the card unless it isremoved in an additional method step. The thickness of the melt adhesivefilm is therefore optimized so as to ensure good adhesion in terms ofthe total surface of the substrate but prevent adhesive material beingsqueezed out of the open places of the edge area of the substrate.However, this leaves no scope for optimizing the melt adhesive film as aprotective buffer zone, using reasonable technical resources.

The invention is therefore based on the problem of proposing a datacarrier with an integrated circuit not involving any additionaltechnical resources, in which even a circuit of larger dimensions canwithstand the mechanical stresses in daily use.

This problem is solved by the features stated in the main claim.

In a preferred embodiment of the invention, the various layers of a datacarrier and the substrate bearing the IC module are pressed togetherusing heat and pressure. The substrate bearing the IC module, the leadsand the contact surfaces is embedded in the laminate in such a way thatthe IC module is disposed in the interior of the data carrier while thecontact surfaces are located on the surface thereof. In order to connectthe substrate with the materials of the data carrier, a melt adhesivefilm is used. In addition a film strip is provided as a separate elementbetween the substrate and the melt adhesive film, said strip beingapproximately as wide and at least as long as the IC module and beingmade of a material having higher deformability than the surroundingmaterials of the data carrier.

The use of this film strip makes it possible to provide an effectivebuffer zone for circuits with larger dimensions as well without havingto adapt the thickness of the melt adhesive film to the size of themodule. The melt adhesive film and the film strip forming the protectivebuffer zone can be optimized in their respective functions independentlyof each other. Whereas the melt adhesive film is selected so as toassure good adhesion of the elements to be connected but preventadhesive material being squeezed out at the open places in the edge areaof the substrate, the film strip, being a separate element, can beoptimized in its dimensions and physical properties so as to protecteven larger IC modules effectively from mechanical stresses.

In spite of these advantages, the use of the film strip does not involveany appreciable additional effort. The integrated circuits suitable forincorporation in identification cards are generally supplied by thesemiconductor producer already mounted on film strips. The incorporationin identification cards of substrates appropriately punched out of thefilm strips, as described in German "offenlegungsschrift" no. 33 38 597,necessitates, as mentioned, an adhesive layer, for example a meltadhesive film. The substrate and melt adhesive film are preferablycombined prior to the card production, the substrate and melt adhesivefilm each being wound off its own roll and brought together and bondedusing heat and pressure, for example, in a roll laminating means. Itdoes not require any additional effort in terms of process technology todispose an additional film strip on the IC module since this strip, alsowound off a roll, can be applied to the substrate film bearing theintegrated module simultaneously with the melt adhesive film. Theadditional film strip is enclosed between the substrate and meltadhesive film. The additional material used per substrate or datacarrier is also negligible in view of the total costs of a data carrier.

In accordance with a further embodiment of the invention, the film stripis made of a material that not only has high elastic deformability butalso has a lower softening temperature than the materials of the datacarrier and furthermore does not bond during the laminating process withthe materials (such as the melt adhesive film, substrate film and alsothe IC module) in the surroundings. Since the film strip is thusplastically deformable and does not bond with the surrounding materialsduring lamination, the IC module and leads can be embedded free fromtension, on the one hand, and move within certain limits inside thelaminate if the data carrier is strongly deformed during use, on theother hand, thereby evading the stresses caused by the deformation inthe laminate. A material having the above-mentioned properties ispolyethylene, for example.

Further advantages and developments of the invention can be found in thesubclaims and in the following description of some embodiments withreference to the figures, in which

FIG. 1 shows an identification card from the top,

FIG. 2 shows a cross-sectional view of the identfication card of FIG. 1prior to lamination,

FIG. 3 shows a cross-sectional view of the identification card of FIG. 1after lamination,

FIG. 4 shows an apparatus for making a carrier element having filmstrips,

FIG. 5 shows a cross-sectional view of the apparatus of FIG. 4 alongline A-B,

FIG. 6 shows the carrier elements made in the apparatus of FIG. 4 fromthe top,

FIG. 7 shows a further embodiment of a carrier element made in theapparatus of FIG. 4,

FIG. 8 shows an identification card and a carrier element before theindividual elements are joined together,

FIGS. 9 and 10 show an embodiment of a carrier element from the top andin cross-section, and

FIGS. 11 and 12 show a further embodiment of a carrier element from thetop and in cross-section.

FIG. 1 shows an identification card 1 having an IC module 3 embedded inthe card core, said module being electrically connected via leads withouter contact surfaces 2 located on the card surface. In a preferredembodiment the card consists of three layers (see FIGS. 2 and 3). a cardcore layer 13 with an opening 16 for IC module 3 and two cover films 14,15, cover film 14 having two recesses 7 and 8. The recesses aredimensioned so that each one can take up a group consisting of fourcontact surfaces in the embodiment shown. Bottom cover film 15 seals offthe identification card on the back. Between core layer 13 and coverlayer 14 there is the so-called carrier element consisting of IC module3, leads 4, contact surfaces 2 and carrier substrate 10. IC module 3 isconnected in a recess 11 of substrate 10 with the ends of leads 4protruding into the recess, and is held in the window only by theattachment of the leads with the corresponding terminals of the module.This type of attachment or positioning of semiconductor elements withleads etched out of a conductive coating of the substrate has been knownfor some time and proved its usefulness in practice (see alsoSiemens-Bauteile-Report 16 (1978), no. 2, pp. 40-44).

To allow the carrier element to be fixed in the card structure, saidelement is underlaid with a melt adhesive film 6. This melt adhesivefilm serves to combine substrate 10, which is made of polyimide, forexample, with the material of the identification card (for example PVC)so that these layers bond when pressed together using heat and pressure.

According to the invention, a strip 5 is provided between melt adhesivefilm 6 and IC module 3, said strip having at least the dimensions of theIC module and covering its bottom area. The film strip is made of amaterial having high elastic deformability, so that the IC module andleads move within certain limits inside the card laminate when the cardis strongly deformed and evade the stresses caused by the deformation inthe card laminate. The material of the film strip preferably has notonly high elastic deformability but also a low softening point comparedto the card materials used. This makes the material plasticallydeformable during lamination, allowing for the IC module and leads to beembedded free from tension. It has also been shown that the protectiveeffect can be further improved by selecting a material, e.g.polyethylene, which not only has a low modulus of elasticity compared toPVC, for example [E (PE)=200-300 N/mm², E (PVC)=3000 N/mm² ] and a lowersoftening point, but also does not bond during the laminating processwith the materials in the surroundings, such as melt adhesive film 6,substrate 10 and also IC module 3. This further improvement in theprotective effect for the circuit is presumably due to the movability ofthe film strip within the card, which is not impaired by any adhesion toadjacent elements.

The advantageous embedding technique described can be realized withoutany appreciable additional effort if the carrier element is alreadyequipped with a film strip before being embedded in an identificationcard.

A corresponding apparatus for making such carrier elements is shown inFIG. 4. The apparatus shown very schematically here essentiallycomprises a so-called roll laminating means consisting of a heating roll26 and a pressure roll 27, as well as a driving means consisting of adrive roll 29 connected to a motor 34, and a mating roll 31. The motorrotates drive roll 29 in the direction of arrow 28. The film strips tobe connected are wound off supply rolls 20, 22, 23 and wound onto astorage roll 21 after passing through the roll laminating and drivingmeans. These elements and others specifically explained below are allattached to a mounting plate 35.

The raw product for making carrier elements is a substrate film 10 onwhich IC modules 3 are mounted at regular intervals by the so-called TABtechnique (tape automated bonding). Film 10 equipped with IC modules 3is wound on a roll 20 in the usual way. Melt adhesive film 6 is directedfrom a supply roll 23 via a deflection roll 25 together with substratefilm 10 between heating and pressure rolls 26, 27. Between heating roll26 and pressure roll 27, melt adhesive film 6 is bonded with substratefilm 10 under the action of heat and pressure. As FIG. 5 shows in across-sectional view, heating roll 26 is provided with a recess 36running around the middle thereof, so that when substrate film 10equipped with IC modules 3 passes through the modules are free frommechanical and thermal stresses. Melt adhesive film 6 is combined withsubstrate film 10 along the edge areas extending in the direction oftransport. Film strip 5 embedded according to the invention between theIC module and melt adhesive film 6 is wound off a supply roll 22 anddirected via deflection roll 24 in the area of the heating and matingrolls between melt adhesive film 6 and substrate film 10. This filmstrip does not bond with the surrounding materials but is only enclosedin the position determined by its introduction by the compoundarrangement of melt adhesive film 6 and substrate film 10. Aftermelting, the film laminate runs through drive and mating rolls 29, 31.Here, the melt adhesive film is again pressed onto the substrate filmwith simultaneous cooling and thereby fixed definitively. The finishedlaminate is finally wound onto storage roll 21.

The end product is shown from the top in FIG. 6. The figure showssubstrate film 10 with contact surfaces 2 located on its surface, andleads 4 which lead to IC module 3 located in a recess. Along a side edgesubstrate film 10 is provided with perforations 12 which may also beused in the apparatus described above to transport substrate film 10accurately during the various processing steps. FIG. 6 indicates thedimensions and the position of film strip 5 embedded between meltadhesive film 6 and substrate film 10. Film strip 5 is approximately aswide as the IC module but extends over the entire length of substratefilm 10. Leads 4 extending into recess 11 to IC module 3 are preferablydirected so as to be also located on passing film strip 5 and thusprotected accordingly.

As shown, film strip 5 protecting IC module 3 and leads 4 can be placedbetween melt adhesive film 6 and substrate film 10 without anyadditional effort in terms of process technology.

In the identification card shown in FIGS. 1 and 3, the various cardlayers are bonded together using heat and pressure. During thelaminating process the substrate is embedded with all components in thecard laminate in such a way that the IC module is located approximatelyin the middle of the card laminate while the contact surfaces are flushwith the card surface. Web 17 made of the material of cover film 14 andextending between the contact areas ensures, among other things, thatthe IC module is pressed into recess 16 of core layer 13, as alsodescribed in German "offenlegungsschrift"no. 33 38 597.

In other known incorporating techniques, the substrate is inserted, forexample, into a prepared recess in a finished identification card. Sinceno further cover layer is provided in this case, the substrate must becovered and thereby protected in a different way in the area of the ICmodule on the side where the contact surfaces are located if theso-called micropack form is to be retained. A further embodiment of theinvention therefore consists in providing a film strip 32 in the middleof substrate 10, as shown in FIGS. 7 and 8. This film strip can also beprovided on the substrate using the apparatus shown in FIG. 4 in asimple manner similar to that described above. For this purpose one needonly provide a further supply roll 33 (shown by dotted lines in FIG. 4)from which an appropriate film strip 32 is wound and directed betweenheating and pressure rolls 26, 27. To allow for film strip 32 to beattached to substrate film 10 said strip can be provided with anadhesive layer 30. Film strip 32 is preferably adapted to the particularcard material, being made, for example, of PVC which is dyed or printedin accordance with the particular card design.

To allow for the latter substrate to be incorporated in anidentification card, finished card 37 is provided with a recess 38adapted to the dimensions of the substrate (FIG. 8). The substrate isconnected with card body 37 using a heating die 39, for example. Due tofilm strip 32 passing through the middle of the substrate, the IC moduleis protected against outer influences in the middle of the card bodylaminate, while the contact surfaces are readily accessible on the cardsurface.

FIGS. 9 and 10 show an embodiment of a substrate suitable forincorporation in identification cards, in which IC module 3 is notlocated in a recess in substrate 10 but covered by material of thesubstrate on the side opposite the contact surfaces (FIG. 10). Thesubstrate has a plurality of recesses 40 through which leads 4 run whichconnect IC module 3 electrically with contact surfaces 2. The entiresubstrate is provided with a conductive coating 42 out of which contactsurfaces 2 with the leads leading to the recesses are etched. Thecontact surfaces are therefore completely surrounded by conductivematerial which is preferably connected to ground contact 2a to protectthe circuit from electrostatic charges in a manner known as such.

The cross-sectional view of FIG. 10 indicates that recesses 40 arefilled with a suitable resin 41 to protect the point of connectionbetween the end of the particular lead and the IC module againstenvironmental influences and mechanical stresses.

In the embodiment shown, a recess 40 is associated with each terminal ofthe module and thus with each lead. It is also possible to direct two ormore leads jointly through one recess to the terminals of the module,depending on the paths of the leads.

The substrate shown in FIGS. 9 and 10 involves the advantage that it canbe used in identification cards without additional measures using theincorporation techniques described above while maintaining thetimetested TAB technique (see also Siemens-Bauteile-Report). Using theincorporation technique explained in connection with FIGS. 1 to 3,middle web 17 of the cover film can be omitted. Using the incorporationvariant explained in connection with FIG. 8, film strip 32 can bedispensed with.

To incorporate the substrate, a melt adhesive film can again be used. Anadditional film strip having the properties described above may also beused with this substrate between the melt adhesive film and the ICmodule.

Finally, FIGS. 11 and 12 show a further embodiment of a carrier elementfor integrated circuits, which is essentially characterized in thatterminals 43 of integrated circuit 3 are not located in the edge area ofthe chip surface, as is usual and shown in FIGS. 10 and 11.

In the carrier element shown by way of example in FIGS. 11 and 12,terminals 43 of the circuit, to which the ends of leads 4 are directedthrough a recess 40 in film 10, are located in the center of the circuitarea. This embodiment involves several advantages.

It is technically easier to handle the filling of cavity 40 with asuitable resin or silicon because the volume of the cavity to be filledvaries only within narrow tolerances.

If the circuit is pressed against film 10 during filling so that thecircuit closes off recess 40 on one side, a cavity 40 having apredefined volume exists which can be filled evenly in a simple mannerin the production process once the dosage is set. Even if there is asmall gap between the circuit and the film, which is also filled in withthe selected resin or silicon during the filling process, it has noadverse effect on the dosage, since the amount flowing in here is smalland varies insignificantly in different carrier elements.

If a transparent resin or silicon gel is selected to fill in the cavity,an irregular closure of the recess on the surface of the carrier elementdoes not disturb the appearance either.

The arrangement of terminals 43 of module 3 shown in the figures alsoinvolves the advantage that the soldered or welded connections betweenthe ends of leads 4 and terminals 43 of the module, due to their centralposition, are subjected to less mechanical load with respect to anytensile or gravitational forces when the carrier element is bent than ifthe terminals are arranged decentrally in the edge area of the circuit.

Finally, the shown placement of terminals 43 on the circuit involves theadvantage that the lead routing and thus also the bonding tool can beretained unchanged for circuits of different sizes.

I claim:
 1. In an integrated circuit semiconductor chip device includingintegrated ccircuitry and electrically conductive terminals on the chipsurface, said surface limited by chip edge boundaries, said terminalsconnected to said integrated circuitry and adapted to be connected toexternal leads for communication between the external leads and theintegrated circuitry, the improvement comprising:said terminals beingdisposed as a group array located over a predetermined area of the chipsurface spaced inwardly from the chip edge boundaries, said areaterminating at area boundaries, at least one area boundary and thegeometric center of said area being closer to the center of the chipsurface than the closest directly opposite chip edge boundary.
 2. Theimprovement in an integrated circuit device as claimed in claim 1,wherein said chip surface includes at least one central zone equidistantfrom at least one pair of opposite edge boundaries and said array ofterminals is disposed in said central zone.